1. Field of the Invention
The present invention generally relates to a method and a system of selecting an object displayed on a computer display screen and a system thereof and, more particularly, to a method of selecting an object constituting a three-dimensional model displayed on the computer display screen with a good ease of use.
2. Background Description
In selecting a particular object among a plurality of objects constituting a three-dimensional model displayed on a computer display screen, it is often very difficult to point to a precise position because (a) an aimed object is hidden by another object, (b) there are many satisfying candidates for selection, or (c) a parallax exists in the direction of depth due to the three-dimensional display. The user has to click again and again or adjust the click position strictly. Such effort is stressful to the user. Such effort also lowers the work efficiency of a user of three-dimensional graphic software.
An example of a prior art solution to this problem is a proposed method of highlighting selected graphic images in the display by a sequential button operation in the direction of the depth (Z axis) of the display to select a desired graphic image when it is highlighted in the display. However, this method involves several disadvantages; e.g., (a) the time when the desired object is highlighted is unknown, (b) of the desired object is found to be absent when all the objects have been viewed sequentially to the last one, and (c) a plurality of objects which can be selected can not be viewed at one glance.
A method of selecting a hidden object by fewer steps of operation is known in PUPA 8-77231. This publication discloses a technique which allows positional relationship of objects to be viewed at a glance by projecting a display object and a hidden object from different directions of view onto an area which is set by a user and re-displaying a two-dimensional graphic image including each object in dispersed relation. However, there are an unlimited number of choices of different view directions in this method so that an effective view direction has to be selected. In addition, this method does not work effectively for the selection of objects in a mode where three-dimensional models are overlapped or included.
As an alternative, PUPA 7-96934 discloses a method of easily selecting an intended object without changing a point of view by selecting an object overlapping a specific range of area relative to the position of a pointer to correlate it to a transparent pop-up menu. The technique disclosed in this publication is for selecting an intended object without losing in enlargement operation an overall view of very crowded line segments as seen in a two-dimensional computer aided design (CAD) display, or the like, and is based on a presumption that the position of the object is known. However, a novel technique is needed because the user does not necessarily point precisely to an object hidden inside complex objects in the case of three-dimension.
A method of presenting a list of parts to a user for selection is included in a CAD system. In this method, it is necessary to know the name of a part in advance. In addition, even if it is known that an object lies in some place around a certain position, it has to be located in a list consisting of several hundreds to several thousands items each time it is selected so that the operation is unrealistic and work efficiency is low in this method.